1. Technical Field
The present invention relates to an optical device and a projector.
2. Related Art
There have been known projectors including an optical modulator that modulates a light beam irradiated from a light source in accordance with image information and a projection optical device that projects the light beam modulated by the optical modulator in an enlarged manner.
As the optical modulator, an optical modulating element (a liquid crystal panel) in which liquid crystal is sealed between a pair of substrates are generally used. On a light incident side and a light emitting side of the optical modulating element, an incident-side polarizer and an irradiation-side polarizer which transmit a light beam having a predetermined polarization axis are respectively disposed.
In the projector that includes optical elements such as the optical modulating element, the incident-side polarizer and the irradiation-side polarizer, heat absorption of the light beam from the light beam source by a liquid crystal layer, a black matrix, wiring and the like often causes temperature rise in the optical modulating element and heat generation in the polarizer.
Accordingly, for the projector that accommodates the above-described optical elements, a technique for cooling the optical elements using a heat pipe has been suggested (see, for instance, a patent document JP-A-2001-312002).
In the technique disclosed in the document, the heat pipe is disposed at a position spaced from the optical elements such as a liquid crystal panel and a cooling fin is in thermal contact with a heat-absorbing portion (an evaporating portion) of the heat pipe. Heat in air in the vicinity of the optical elements such as the liquid crystal panel is transferred to the cooling fin. The heat in the cooling fin is absorbed by the heat pipe, transferred to a heat releasing portion (a condensing portion) of the heat pipe to be released.
However, since the technique disclosed in the document cools the optical element via the air, thermal resistance in the heat transfer from the air to the evaporating portion (the cooling fin) of the heat pipe is large, so that it is difficult to lower the temperature of the air. As a result, the optical elements cannot be efficiently cooled.